Hydraulic device

ABSTRACT

A hydraulic device comprising a plurality of hydraulic cylinders, a synchronizing device having fluid chambers of the same number as that of the hydraulic cylinders but having far smaller inside volume than that of the hydraulic cylinders, each fluid chamber including a synchronizing piston within the chamber, all of said pistons being rigidly connected together so that the pistons are operable simultaneously, and transfer valves of a number equal to that of the hydraulic cylinders, cylinder heads of the hydraulic cylinders being connected to cells formed at one side of the fluid chambers of the synchronizing device, cells formed at another side of the fluid chambers being connected to a pressurized fluid source, and the transfer valves being connected in these connection lines.

United States Patent 1 Aoki Nov. 6, 1973 [54] HYDRAULIC DEVICE [76] Inventor: Katashi Aoki, 6037, Oaza Minamijo, Sakaki-machi, Hanishina-gun, Nagano-ken, Japan [22] Filed: June 9, 1971 [21] Appl. No.: 151,393

[30] Foreign Application Priority Data June 17, 1970 Japan 45/52077 [52] US. Cl 91/171, 91/275, 91/448,

[51] Int. Cl. F01b 25/04, F15b 11/22 [58] Field of Search 91/171; 60/97 E [56] References Cited UNITED STATES PATENTS 1,831,238 ll/193l Ferris 60/97 E 2,410,603 lI/l946 Dubosclard 9l/l7l FOREIGN PATENTS OR APPLICATIONS 1,044,625 ll/l958 Germany 60/9 7 E Primary ExaminerPaul E. Maslousky AtzomeyDavid H. Semmes [57] ABSTRACT A hydraulic device comprising a plurality of hydraulic cylinders, a synchronizing device having fluid chambers of the same number as that of the hydraulic cylinders but having far smaller inside volume than that of the hydraulic cylinders, each fluid chamber including a synchronizing piston within the: chamber, all of said pistons being rigidly connected together so that the pistons are operable simultaneously, and transfer valves of a number equal to that of the hydraulic cylinders, cylinder heads of the hydraulic cylinders being connected to cells formed at one side of the fluid chambers of the synchronizing device, cells formed at another side of the fluid chambers being connected to a pressurized fluid source, and the transfer valves being connected in these connection lines.

4 Claims, 4 Drawing Figures HYDRAULIC DEVICE BACKGROUND OF THE INVENTION Thisinvention relatesto a hydraulic device wherein a plurality of hydraulic cylinders are operated in ,synchronism.

Heretofore, when a plurality of hydraulic cylinders harmful effect of the leakagewin the synchronizing de vice is accumulated in the plurality of hydraulic cylinders, causing thesynchronizedoperation of the plurality of cylinders to be utterly unattainable without having an intermediate adjustment for the quantities of the pressurized fluid in these cylinders.

SUMMARY OF THE INVENTION Therefore, a primary objectof the presentinvention is to provide an improved hydraulic device wherein all of the drawbacks of theconventional hydraulic devices are. totally eliminated.

Another objectof the present invention is to provide a hydraulic device wherein theoperation ofa plurality of hydraulic. cylinders can be achieved through asynchronizing device of a simple construction requiring no manual adjustment for a longperiodof operation.

The synchronizingdevice, constituting an important part of the presentwinvention, comprises fluid chambers ofthe-same numbervas that of thehydraulic cylinders but having a far smaller inside volume than thatof the. hydraulic cylinder, and pistons eachincluded in one of the fluid chambers. All of the pistonsare rigidly connected togetherso that those pistons are operated simultaneously in all of the hereinafter described operations ofthe synchronizing device. Furthermore, all of the fluid lines connected to the hydraulic cylinder heads of the hydraulic device are connected'to either side of cells formed inside of thefluidrchambers bythe existence of the pistons of the synchronizing device, so that the pressurizedfluid is-suppliedtinto or delivered out of the hydraulic. cylindersthrough thecells inside of the synchronizingdevice under. thecontrol of a corresponding number of transfer valves; The transfer valves are operated far frequently than the operation cycles of the. hydraulic cylinders so that the'pressurized fluid supplied to cells on either side of the synchronizing device is consecutively sent to the'hydrauliccylin- .ders.

More specifically, each of the transfer valves is inter posed between a pressurizedfluidsource and a cylinder head of the hydraulic cylinders, and the transfer valve is electrically operated at an instant the. displacement of the synchronizing pistons integrally combined.

reaches its extremity under the action ofthe'pressurized fluid introduced into one. side of the cells, whereby the side of cells supplied with the pressurized fluid is exchanged and the synchronizing pistons are moved to the opposite direction. The reversed movement of the synchronizing pistons forces out the previously introduced pressurized fluid to the cylinder head corresponding to the specific fluid chamber until the displacement of the piston reaches to its extremity. The same operation is repeated when the transfer valve is again operated electrically.

The invention will be betterunderstood from the following detailed description with respect to preferred embodiments thereof when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIGS. 1 and 2 are schematic views, partly in section, of a hydraulic device constituting a preferred embodiment of the present invention at respective instants during the upward movement of the pistons;

FIG. 3 is a schematic view, partly in section, of a hydraulic device of the same embodiment at an instant during the downward movement of the piston; and

FIG. 4 is a schematic view, partly in section, of a hy-, draulic device constituting another embodiment of the. invention.

DETAILED DESCRIPTION In the drawings, there are indicated hydraulic cylinders 1, 1' including pistons 10, 10, respectively, asynchronizing device generally denoted by 2, transfer valves 3, 3', and a fluid direction change-over valve 4.

The above described synchronizing device 2. com prises fluid chambers 5, 5' of the same. number as that of the hydraulic cylinders l, 1' but having far smaller inner volumes than those of the latter cylinders, and

synchronizing pistons 6, 6' included in these. fluid chambers 5,5, respectively, and the synchronizingpistons 6, 6 are rigidly connected together by means of tie plates 7, 7' attached to both, ends ofthesepistons 6, 6'.

The hydraulic cylinders l, 1' are respectively divided into two chambers A, C, and A, C. by theexistence of the pistons 10, 10', and each of the fluidchambers 5,

5* is also divided into two synchronizingcells B, D, and

B, D by means of the synchronizing pistons 6, 6. The chamber A and cell B, and the chamber A and cell B are respectively connected by fluid lines 8, 8', and the chambers C, C, and cells D, D are all connected to the.

fluid-direction change-over valve4' throughfluid lines 9, 11, and 11' respectively.

The transfer valves 3, 3' for supplying pressurized.

fluid to the synchronizing device 2 are disposed respec tively between hydraulic cylinders l, I and the. syn.-

chronizing device 2, so that the transfer valves3, 3 can act for both of the fluid lines 8, 11,.and8', 111', respectively. That is, the pressurized fluid is alternately sent into the cells B, B', and D, D under the transferringioperation of the transfer valves-3,3, andalso is sent to the chambers A, A inthe hydraulic cylinders 1,1.

The operation. of the hydrauliedlevice accordingtothe present invention will now be. explained.

In'the state shown in FIG. 1, thepressurizedlfluidP passedthrough the changeover valve 41 is-divideduinto two parts followingthe fluidlines 111, 1 1" which are thereafter guided into cellsD, Dof the synchronizing-a device Zthrough the transfer valves 3,.3, pushing up the rigidly connected synchronizing pistons 6,6. Upon the displacements of the synchronizing pistons 6, 6 upwardly, the pressurized fluid in the cells B, B is respectively sent into the chambers A, A of the hydraulic cylinders 1, 1, whereby the pistons 10, 10' are forced upwardly.

When the displacements of the synchronizing pistons 6, 6' reach their upward ends, the two transfer switches 3, 3 are transferred into another position as shown in FIG. 2 under an electrical control of, for instance, a limit switch SWI, schematically shown in FIG. 1, operated by the piston rods or tie plates of the synchronizing pistons, whereby the pressurizing fluid is introduced into the cells B, B, sending out the pressurizing fluid previously introduced into the cells D, D to the chambers A, A of the hydraulic cylinders 1, 1'.

With the repeated operation of the above described cycles, the pressurized fluid sent into the chambers 5, 5' of the synchronizing device 2 is successively and by a constant amount supplied into the hydraulic cylinders 1, l by means of the synchronizing pistons 6, 6' operated simultaneously because of the rigid combination therebetween, whereby the two pistons 10, 10 are elevated upwardly under the same pressure and at the same speed.

When it is desired to descend the pistons 10, 10, the fluid direction change-over valve 4 is transferred to a position as shown in FIG. 3. The pressurized fluid P is now sent into the chambers C, C of the hydraulic cylinders I, 1 through the fluid line 9. Accordingly, the pistons l0, 10 are descended and the pressurized fluid in the chambers A, A is exhausted through the lines 8, 8' into the cells B, B of the synchronizing device 2, whereby the rigidly combined pistons 6, 6' are shifted downwardly. As a result, the fluid in the cells D, D are exhausted through lines l1, 11' respectively to the change-over valve 4 and thereafter to a reservoir of the pressurized fluid (not shown). When the displacements of the pistons 6, 6' reach their terminal points, the transfer valves 3, 3 are transferred their positions automatically same as the condition when the transfer valves 3, 3 are transferred as shown in FIG. 2, under the electrical direction of, for instance, a limit switch SW2, (FIG. 1) and the pressurized fluid is now sent into the cells D, D moving the synchronizing pistons 6, 6 upwardly, and sending back the fluid in the cells B, B through lines 11, 11' to the change-over valve 4 and to the reservoir. Finally when the pressurized fluid in the chambers A, A is completely exhausted, the pistons l0, 10' are descended to their lowermost positions.

In FIG. 4, there is indicated another embodiment of the present invention, wherein the fluid chambers 5, 5' in the synchronizing device 2 are disposed longitudinally on a single shaft. That is, the synchronizing pistons 6, 6' included in these chambers 5, 5' are mounted on the single shaft 12 so that the pistons 6, 6 are combined rigidly in a cooperative state. The operation of this embodiment is quite the same as the previous embodiment of the invention shown in FIGS. 1 through 4.

In all of the above described embodiments, although the number of the hydraulic cylinders has been indicated as two for the simplification of the drawings, it will be apparent that the number of the cylinders may also be more than 2, and with the provision of corresponding number of synchronizing chambers and pistons of the synchronizing device, all of the hydraulic cylinders can be operated in synchronism in the upward or downward movement. As a result, it is also apparent that the present invention is not always limited to the above described two embodiments.

Since the construction of the present invention is as disclosed above, the hydraulic cylinders can be operated in synchronism under the reciprocating operations of the synchronizing pistons included in the fluid chambers of the synchronizing device.

Furthermore, when one of the transfer valves would have a trouble, the flowing direction of the fluid due to the transfer of other transfer valves opposes the pressurized fluid caused by the faulty transfer valve, whereby the two synchronizing pistons subjecting to the oppositely directing pressurized fluids are stopped .their movements, causing interruption of the supply of the pressurized fluid. As a result, any possibility of only one of the hydraulic cylinders is operated due to the failure of a transfer valve is utterly eliminated. In addition, the construction of the synchronizing device and the arrangement of the fluid lines are also much simplified, whereby the manufacturing cost of the hydraulic device is substantially reduced.

What is claimed is:

l. A hydraulic device comprising:

A. a plurality of hydraulic cylinders having piston heads movably mounted therein and dividing said cylinders into first and second cylinder chambers;

B. a synchronizing device having fluid chambers equal in number to said hydraulic cylinders, but of smaller inside volumes than said hydraulic cylinders;

C. each of said fluid chamber including a synchronizing piston within and dividing said fluid chamber into first and second synchronizer cells;

D. said synchronizing pistons being rigidly connected together and simultaneously operable;

E. a source of fluid pressure;

F. a first set of lines operatively connecting said first cylinder cells to said source of fluid pressure;

G. a second set of lines operatively connecting said second cylinder cells to said first synchronizer cells;

H. A third set of lines operatively connecting said second synchronizer cells to said source of fluid pressure;

. transfer valves of a number equal to that of the hydraulic cylinders connected into both said sets of lines opening into said synchronizer cells operable for controlling flow selectively into and out of said first and second cylinder cells upon movement of said pistons in opposite predetermined directions; and

.I. a fluid direction changeover valve interconnected in both said sets of lines leading to said source of fluid pressure.

2. A hydraulic device as claimed in claim 1, including means operable upon movement of said synchronizing pistons to predetermined upper and lower end positions to switch said transfer valves to reverse flow into and out of said first and second synchronizer cells and thereby into and out of said first and second cylinder chambers to move said piston heads in said hydraulic cylinders.

3. A hydraulic device as in claim 2 wherein said synchronizing cells of said synchronizing device are disposed in parallel, and respective opposite ends of the synchronizing pistons are rigidly connected by means of tie plates so that the synchronizing pistons are operaposed in series, and said synchronizing pistons included ble in unison. in the series are mounted on a single shaft provided 4. A hydraulic device as in claim 2 wherein said synthrough said cells.

chronizer cells of said synchronizing device are dis- 

1. A hydraulic device comprising: A. a plurality of hydraulic cylinders having piston heads movably mounted therein and dividing said cylinders into first and second cylinder chambers; B. a synchronizing device having fluid chambers equal in number to said hydraulic cylinders, but of smaller inside volumes than said hydraulic cylinders; C. each of said fluid chamber including a synchronizing piston within and dividing said fluid chamber into first and second synchronizer cells; D. said synchronizing pistons being rigidly connected together and simultaneously operable; E. a source of fluid pressure; F. a first set of lines operatively connecting said first cylinder cells to said source of fluid pressure; G. a second set of lines operatively connecting said second cylinder cells to said first synchronizer cells; H. A third set of lines operatively connecting said second synchronizer cells to said source of fluid pressure; I. transfer valves of a number equal to that of the hydraulic cylinders connected into both said sets of lines opening into said synchronizer cells operable for controlling flow selectively into and out of said first and second cylinder cells upon movement of said pistons in opposite predetermined directions; and J. a fluid direction changeover valve interconnected in both said sets of lines leading to said source of fluid pressure.
 2. A hydraulic device as claimed in claim 1, including means operable upon movement of said synchronizing pistons to predetermined upper and lower end positions to switch said transfer valves to reverse flow into and out of said first and second synchronizer cells and thereby into and out of said first and second cylinder chambers to move said piston heads in said hydraulic cylinders.
 3. A hydraulic device as in claim 2 wherein said synchronizing cells of said synchronizing device are disposed in parallel, and respective opposite ends of the synchronizing pistons are rigidly connected by means of tie plates so that the synchronizing pistons are operable in unison.
 4. A hydraulic device as in claim 2 wherein said synchronizer cells of said synchronizing device are disposed in series, and said synchronizing pistons included in the series are mounted on a single shaft provided through said cells. 